Maryland Journeyperson Electrician

An ammeter is connected in series and must have very low internal resistance to measure current, while a voltmeter is connected in parallel and must have very high internal resistance to measure potential difference without drawing significant current.

The grounded (neutral) conductor's continuity shall NOT depend on connection to metallic enclosures, raceways, or cable armor, whereas equipment grounding conductors may use metallic raceways as the grounding path.

The earth shall NOT be considered an effective ground-fault current path; an effective path must be a low-impedance circuit capable of safely carrying maximum ground-fault current and facilitating overcurrent device operation.

Type MC cable without an overall nonmetallic covering is permitted in spaces used for environmental air (plenums), while Type NM, ENT, and PVC are not permitted in plenum spaces unless enclosed in an approved metal raceway.

FMC is prohibited in wet locations, whereas LFMC in trade sizes 3/4 through 1-1/4 may serve as an equipment grounding conductor when the OCPD is rated ≤60 A and the total length in the ground-fault path does not exceed 6 ft.

A single rod, pipe, or plate electrode requires a supplemental electrode unless its resistance to earth is 25 ohms or less, while a concrete-encased electrode requires at least 20 ft of rebar (≥1/2 in. diameter) or 4 AWG bare copper encased in at least 2 inches of concrete.

For a separately derived system, the system bonding jumper may be installed at any single point from the source to the first disconnecting means, whereas standard locknuts or bushings alone are not acceptable as the sole bonding method at a service.

At a separate detached building supplied by a feeder with its own disconnect and grounding electrode, the grounded (neutral) conductor shall NOT be connected to the equipment grounding conductor or grounding electrode, unlike at the main service where this bond is required.

Even when conductors are rated 90°C, the ampacity must be limited to the 75°C column value when terminations are not listed and marked for use above 75°C on circuits over 100 A or conductors larger than 1 AWG.

On wiring-plan blueprints, a single-pole switch is denoted by a plain 'S', while a three-way switch is denoted by 'S' with a subscript '3' (S3).

Where a cable passes through bored holes and maintains at least 1-1/4 inches from the nearest wood-member edge, no additional protection is needed; when that distance cannot be maintained, a steel plate or sleeve at least 1/16 inch thick must be installed.

For Type MI cable with an external diameter greater than 3/4 in. but not more than 1 in., the minimum inner-edge bending radius is ten times the external diameter, whereas the multiplier differs for smaller diameters.